Use of Biocide-Containing, Water-Redispersible Polymer Powder Compositions in Mineral Construction Materials

ABSTRACT

Mineral construction materials such as mortars and tile adhesives are rendered more resistant to microbial growth by adding biocide in the form of a biocide-containing redispersible polymer powder rather than adding biocide separately.

The invention relates to the use of biocide-containing,water-redispersible polymer powder compositions in mineral buildingcompositions.

Mineral building compositions, for example lime- or cement-bondedbuilding materials such as plasters and renders, knifing fillers andbuilding adhesives need to be protected against weathering influencesand microbiological attack by microorganisms, fungi and algae.Particularly under moist weathering conditions, exterior walls areregularly damaged after a few years by growth of algae and fungi if theyare not protected by means of appropriate measures. This is alleviatedin practice by use of fungicides and/or algicides which are added inhigh active compound concentrations to the building materials in the drymortar works or on the building site (film preservation). A disadvantageof this is that these active compounds are quickly degraded under thestrongly basic conditions prevailing in the liquid buildingcompositions, and for this reason appropriately large amounts have to beused or the effectiveness decreases considerably over the course oftime.

In the use of polymer dispersions, pot preservation has long been priorart in order to protect the aqueous product against microbiologicalattack. For this purpose, use is made first and foremost of biocidallyactive compounds.

Water-redispersible powders based on homopolymers or copolymers ofethylenically unsaturated monomers are used as binders in the buildingsector, for example in combination with hydraulically setting binderssuch as cement. These serve, for example, to improve the mechanicalstrength and the adhesion in building adhesives, plasters and renders,mortars and paints. Microbiogically active additives have hitherto notbeen employed in the preparation and use of redispersion powders, sincethese systems are not prone to attack in the dry state. Theseredispersion powders corresponding to the prior art therefore make nocontribution to the protection of coatings on the outside of buildingsagainst microbiological attack and attack by algae and fungi.

EP-A 862856 discloses the use of crop protection agents such aspesticides in combination with a redispersible polymer powder forretarded liberation of the active components. WO-A 00/05275 describesredispersible polymer powders as inert carrier substances for activecomponents, for example for crop protection agents and medicaments.WP10105 discloses coating compositions containing fungicides ascomplexes with cyclodextrin.

It is therefore an object of the invention to provide a redispersibledispersion powder for building compositions, which when used fortreating exterior coatings also proves to be effective against attack bymicroorganisms, algae and fungi.

The invention provides for the use of biocide-containing,water-redispersible polymer powder compositions in mineral buildingcompositions, with the water-redispersible polymer powder compositionsbased on a film-forming polymer containing from 0.001 to 0.5% by weightof a biocidally active additive.

For the purposes of the present invention, biocides or biocidally activeadditives are bactericides, fungicides and algicides.

Suitable biocides are commercially available. Active compounds from theclass of isothiazolinone and benzimidazole preservatives are usuallyused against attack by bacteria, yeasts, fungi and algae. Examples areN-octylisothiazolinone, dichloro-N-octylisothiazolinone,chloromethylisothiazolinone, methylisothiazolinone, benzisothiazolinone.Further suitable biocides are benzimidazole derivatives, e.g.2-(methoxycarbonylamino)benzimidazole,2,4-diamino-6-methylthio-1,3,5-triazine derivatives, o-phenylphenol,substituted ureas and phenylureas, phthalimide derivatives, e.g.N-(trichloromethylthio)phthalimide, iodocarbamate, pyrethroids,chloroacetamide, sodium borate, methylisopropylphenol, bariummetaborate, dithiocarbaminates.

The active compound content is set as a function of the effectivenessand the objective to be achieved. In general, a content of from 0.001 to0.5% by weight, preferably from 0.001 to 0.2% by weight, particularlypreferably from 0.001 to 0.1% by weight, in each case based on the totalweight of the water-redispersible polymer powder composition, isemployed.

Suitable film-forming polymers are polymers based on one or moremonomers from the group consisting of vinyl esters, (meth)acrylicesters, vinylaromatics, olefins, 1,3-dienes and vinyl halides and, ifappropriate, further monomers which are copolymerizable therewith.

Suitable vinyl esters are vinyl esters of carboxylic acids having from 1to 12 carbon atoms. Preference is given to vinyl acetate, vinylpropionate, vinyl butyrate, vinyl 2-ethylhexanoate, vinyl laurate,1-methylvinyl acetate, vinyl pivalate and vinyl esters of α-branchedmonocarboxylic acids having from 9 to 11 carbon atoms, for exampleVeoVa9^(R) or VeoVa10^(R) (trade names of Shell). Vinyl acetate isparticularly preferred.

Suitable monomers from the group consisting of acrylic esters andmethacrylic esters are esters of unbranched or branched alcohols havingfrom 1 to 15 carbon atoms. Preferred methacrylic esters and acrylicesters are methyl acrylate, methyl methacrylate, ethyl acrylate, ethylmethacrylate, propyl acrylate, propyl methacrylate, n-butyl acrylate,n-butyl methacrylate, t-butyl acrylate, t-butyl methacrylate,2-ethylhexyl acrylate. Particular preference is given to methylacrylate, methyl methacrylate, n-butyl acrylate, t-butyl acrylate and2-ethylhexyl acrylate.

Preferred vinyl aromatics are styrene, methylstyrene and vinyltoluene. Apreferred vinyl halide is vinyl chloride. Preferred olefins areethylene, propylene and preferred dienes are 1,3-butadiene and isoprene.

If desired, from 0.1 to 5% by weight, based on the total weight of themonomer mixture, of auxiliary monomers can be copolymerized. Preferenceis given to using from 0.5 to 2.5% by weight of auxiliary monomers.Examples of auxiliary monomers are ethylenically unsaturatedmonocarboxylic and dicarboxylic acids, preferably acrylic acid,methacrylic acid, fumaric acid and maleic acid; ethylenicallyunsaturated carboxamides and nitriles, preferably acrylamide andacrylonitrile; monoesters and diesters of fumaric acid and maleic acid,e.g. the diethyl and diisopropyl esters and maleic anhydride,ethylenically unsaturated sulfonic acids or their salts, preferablyvinylsulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid. Furtherexamples are precrosslinking comonomers such as multiply ethylenicallyunsaturated comonomers, for example divinyl adipate, diallyl maleate,allyl methacrylate or triallyl cyanurate, or postcrosslinkingcomonomers, for example acrylamidoglycolic acid (AGA), methylmethylacrylamidoglycolate (MMAG), N-methylolyacrylamide (NMA),N-methylolmethacrylamide, N-methylolallylcarbamate, alkyl ethers such asisobutoxy ether or esters of N-methylolacrylamide, ofN-methylolmethacrylamide and of N-methylolallyl-carbamate. Also suitableare epoxy-functional comonomers such as glycidyl methacrylate andglycidyl acrylate. Further examples are comonomers having a silylfunction, e.g. acryloxypropyltri(alkoxy)silanes andmethacryloxy-propyltri(alkoxy)silanes, vinyltrialkoxysilanes andvinylmethyldialkoxysilanes, in which, for example, ethoxy radicals andethoxypropylene glycol ether radicals can be present as alkoxy groups.Mention may also be made of monomers containing hydroxy or CO groups,for example hydroxyalkyl methacrylates and acrylates, e.g. hydroxyethyl,hydroxypropyl or hydroxybutyl acrylate or methacrylate, and alsocompounds such as diacetoneacrylamide and acetylacetoxyethyl acrylate ormethacrylate.

The choice of monomer or the choice of the proportion by weight of thecomonomers is made so that, in general, a glass transition temperatureTg of ≦40° C., preferably from −10° C. to +25° C., results. The glasstransition temperature Tg of the polymers can be determined in a knownmanner by means of differential scanning calorimetry (DSC). The Tg canalso be calculated approximately beforehand by means of the Foxequation. According to Fox T. G., Bull. Am. Physics Soc. 1, 3, page 123(1956): 1/Tg=x₁/Tg₁+x₂/Tg₂+ . . . +x_(n)/Tg_(n), where x_(n) is the massfraction (% by weight/100) of the monomer n and Tg_(n) is the glasstransition temperature in kelvin of the homopolymer of the monomer n. Tgvalues for homopolymers are listed in the Polymer Handbook 2nd Edition,J. Wiley & Sons, New York (1975).

Preference is given to homopolymers or copolymers comprising one or moremonomers from the group consisting of vinyl acetate, vinyl esters ofα-branched monocarboxylic acids having from 9 to 11 carbon atoms, vinylchloride, ethylene, methyl acrylate, methyl methacrylate, ethylacrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate,n-butyl acrylate, n-butyl methacrylate, 2-ethylhexyl acrylate, styrene.Particular preference is given to copolymers comprising vinyl acetateand ethylene; comprising vinyl acetate, ethylene and a vinyl ester ofα-branched monocarboxylic acids having from 9 to 11 carbon atoms;comprising n-butyl acrylate and 2-ethylhexyl acrylate and/or methylmethacrylate; comprising styrene and one or more monomers from the groupconsisting of methyl acrylate, ethyl acrylate, propyl acrylate, n-butylacrylate, 2-ethylhexyl acrylate; comprising vinyl acetate and one ormore monomers from the group consisting of methyl acrylate, ethylacrylate, propyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate andoptionally ethylene; comprising 1,3-butadiene and styrene and/or methylmethacrylate and optionally further acrylic esters; with the mixedsuspension being able, if desired, to contain one or more of theabovementioned auxiliary monomers.

The greatest preference is given to polymers of the abovementionedcompositions which contain from 0.1 to 5% by weight, based on the totalweight of the polymer, of monomer units derived from one or morecomonomers from the group consisting of ethylenically unsaturatedmonocarboxylic and dicarboxylic acids, e.g. acrylic acid, methacrylicacid, fumaric acid and maleic acid; ethylenically unsaturatedcarboxamides and nitriles such as acrylamide and acrylonitrile;monoesters of fumaric acid and maleic acid and also maleic anhydride,ethylenically unsaturated sulfonic acids and their salts, preferablyvinylsulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid.

The film-forming polymers are prepared by the emulsion polymerizationprocess or by the suspension polymerization process in the presence ofprotective colloids and/or emulsifiers, preferably by the emulsionpolymerization process, with the polymerization temperature generallybeing from 40° C. to 100° C., preferably from 60° C. to 90° C., and withthe polymerization also being able to be carried out undersuperatmospheric pressure, in general at a pressure of from 5 bar to 100bar, in the case of copolymerization of gaseous comonomers such asethylene. Initiation of the polymerization is carried out using thewater-soluble or monomer-soluble initiators or redox initiatorcombinations customary for emulsion polymerization or suspensionpolymerization, as the case may be. Examples of water-soluble initiatorsare sodium persulfate, hydrogen peroxide, azobisisobutyronitrile.Examples of monomer-soluble initiators are dicetyl peroxydicarbonate,dicylcohexyl peroxydicarbonate, dibenzoyl peroxide. The initiatorsmentioned are generally used in an amount of from 0.01 to 0.5% byweight, based on the total weight of the monomers. Redox initiators usedare combinations of the above-mentioned initiators in combination withreducing agents. Suitable reducing agents are, for example, sodiumsulfite, sodium hydroxymethanesulfinate and ascorbic acid. The amount ofreducing agent is preferably from 0.01 to 0.5% by weight, based on thetotal weight of the monomers.

To control the molecular weight, regulating substances can be usedduring the polymerization. If regulators are used, they are usually usedin amounts of from 0.01 to 5.0% by weight, based on the monomers to bepolymerized, and are introduced separately or else as a premix withreaction components. Examples of such substances are n-dodecylmercaptan, tert-dodecyl mercaptan, mercaptopropionic acid, methylmercaptopropionate, isopropanol and acetaldehyde. Preference is given tousing no regulating substances.

Suitable protective colloids are partially hydrolysed or fullyhydrolysed polyvinyl alcohols; polyvinylpyrrolidones; polyvinyl acetals;polysaccharides in water-soluble form, e.g. starches (amylose andamylopectin), celluloses and their carboxymethyl, methyl, hydroxyethyl,hydroxypropyl derivatives; proteins such as casein or caseinate, soyprotein, gelatin; lignosulfonates; synthetic polymers such aspoly(meth)acrylic acid, copolymers of (meth)acrylates withcarboxy-functional comonomer units, poly(meth)acrylamide,polyvinylsulfonic acids and their water-soluble copolymers;melamineformaldehydesulfonates, naphthalene-formaldehydesulfonates,styrene-maleic acid and vinyl ether-maleic acid copolymers. Preferenceis given to partially hydrolysed or fully hydrolysed polyvinyl alcohols.Particular preference is given to partially hydrolysed polyvinylalcohols having a degree of hydrolysis of from 80 to 95 mol % and aHöppler viscosity in 4% strength aqueous solution of from 1 to 30 mPas(Höppler method at 20° C., DIN 53015).

Suitable emulsifiers which can be used in an amount of from 0.5 to 10%by weight based on the amount of monomers can be either anionic,cationic or nonionic emulsifiers, for example anionic surfactants suchas alkyl sulfates having a chain length of from 8 to 18 carbon atoms,alkyl ether sulfates or alkylaryl ether sulphates having from 8 to 18carbon atoms in the hydrophobic radical and up to 40 ethylene oxide orpropylene oxide units, alkylsulfonates or alkylarylsulfonates havingfrom 8 to 18 carbon atoms, esters and monoesters of sulfosuccinic acidwith monohydric alcohols or alkylphenols, or nonionic surfactants suchas alkyl polyglycol ethers or alkylaryl polyglycol ethers having from 8to 40 ethylene oxide units.

After the polymerization is complete, an after-polymerization can becarried out by means of known methods, for example byafter-polymerization initiated by means of a redox catalyst, to removeresidual monomers. Volatile residual monomers can also be removed bymeans of distillation, preferably under reduced pressure, and, ifdesired, with inert stripping gases such as air, nitrogen or steam beingpassed through or over the liquid. The aqueous dispersions which can beobtained in this way have a solids content of from 30 to 75% by weight,preferably from 50 to 60% by weight.

To prepare the biocide-containing, water-redispersible polymer powdercompositions, the biocides are mixed in the amount indicated into theaqueous dispersions, and the dispersions are, if appropriate afteraddition of protective colloids as atomizing aids, dried, for example bymeans of fluidized-bed drying, freeze drying or spray drying. Thedispersions are preferably spray dried. Spray drying is carried out incustomary spray drying units, with atomization being able to be effectedby means of single-fluid, two-fluid or multifluid nozzles or by means ofa rotating disk. The outlet temperature is generally in the range from45° C. to 120° C., preferably from 60° C. to 90° C., depending on theunit, the Tg of the resin and the desired degree of drying.

In general, the atomization aid is used in a total amount of from 3 to30% by weight, based on the polymeric constituents of the dispersion,i.e. the total amount of protective colloid prior to the dryingprocedure should be at least from 3 to 30% by weight, based on theproportion of polymer. Preference is given to using from 5 to 20% byweight, based on the proportion of polymer.

Suitable atomization aids are, for example, the protective colloidswhich have been mentioned above. Preference is given to using no furtherprotective colloids other than polyvinyl alcohols as atomization aid.

A content of up to 1.5% by weight of antifoam, based on the basepolymer, has frequently been found to be advantageous for atomization.To increase the storage stability by improving the blocking resistance,particularly in the case of powders having a low glass transitiontemperature, the powder obtained can be treated with an antiblockingagent (anticaking agent), preferably in an amount of up to 30% byweight, based on the total weight of polymeric constituents. Examples ofantiblocking agents are Ca carbonate or Mg carbonate, talc, gypsum,silica, kaolins, silicates having particle sizes which are preferably inthe range from 10 nm to 10 μm.

To make the powders hydrophobic, one or more hydrophobicizing agentsfrom the group consisting of fatty acids and fatty acid derivatives andorganosilicon compounds can be added to the dispersions prior to drying.Compounds which are suitable for this purpose are listed, for example,in DE-A 10323205.

The viscosity of the feed to be atomized is set via the solids contentso that a value of <500 mPas (Brookfield viscosity at 20 revolutions perminute and 23° C.), preferably <250 mPas, is obtained. The solidscontent of the dispersion to be atomized is >35%, preferably >40%.

As an alternative, the biocides can, if they are present in solid form,be subsequently mixed as powder into the dried polymer dispersion.

These biocide-containing dispersion powders can be used in a variety ofmineral building compositions, for example in conjunction withhydraulically setting binders such as cements (portland, alumina, trass,slag, magnesia, phosphate cement) or water glass, or ingypsum-containing compositions, in lime-containing compositions orcement-free compositions and compositions bound by means of polymers.They are preferably used for the production of building adhesives, inparticular tile adhesives and thermal insulation adhesives, and also inplasters and renders, knifing fillers, flooring screeds, levelingcompositions, sealing slurries, jointing mortars and paints, and alsofor sealing membranes in tunnel construction and underground works.

These redispersion powders are particularly advantageously used in thetreatment of coatings in the exterior sector, which can in this way beprotected against microbiological attack using significantly loweractive compound contents than those employed hitherto. The resultsobtained indicated that the amount of biocide used can be reduced by afactor of 10 or more, with corresponding economic, ecological andoccupational safety advantages.

The following examples illustrate the invention:

EXAMPLE 1

A polyvinyl alcohol-stabilized dispersion of a copolymer of vinylacetate, vinyl versatate (Veova10) and ethylene having a glasstransition temperature of 5° C. is admixed with 10 parts (solid/solid)of a polyvinyl alcohol having a degree of hydrolysis of 88 mol % and aHöppler viscosity of 4 mPas and adjusted to a solids content of 35%.N-Octylisothiazolinone (in the form of Acticide OTW) is added to thisdispersion in an amount corresponding to an active compound content of750 ppm based on powder and the dispersion is spray dried.

EXAMPLE 2

A polyvinyl alcohol-stabilized dispersion of a copolymer of vinylacetate, vinyl versatate (Veova10) and ethylene having a glasstransition temperature of 5° C. is admixed with 10 parts (solid/solid)of a polyvinyl alcohol having a degree of hydrolysis of 88 mol % and aHöppler viscosity of 4 mPas and adjusted to a solids content of 35%.N-Octylisothiazolinone (in the form of Parmetol DF18) is added to thisdispersion in an amount corresponding to an active compound content of350 ppm based on powder and the dispersion is spray dried.

COMPARATIVE EXAMPLE 3

The procedure of Examples 1 and 2 was repeated, but without addition ofbiocide.

Use Test:

A render was formulated as indicated in Table 1 using the dispersionpowders from Examples 1 and 2 and Comparative Example 3 and applied toan exterior wall.

TABLE 1 70.0 parts by weight Dyckerhoff white cement 456.3 parts byweight chalk (calcite 500) 282.5 parts by weight chalk (calcite 0.5-1.0)67.5 parts by weight slagged lime 70.0 parts by weight chalk (Omya BL)14.5 parts by weight titanium dioxide (Kronis 2959) 4.4 parts by weightfiber (Arbocel BC 1000) 1.7 parts by weight mineral thickener (LancoThix P12) 1.6 parts by weight methylcellulose (Tyolose NH 10001 P4) 30.0parts by weight dispersion powder 25.0 parts by weight water per 100parts by weight of dry mix

COMPARATIVE EXAMPLE 4

The biocide-free powder from Comparative Example 3 was used in theformulation and 225 ppm of N-octylisothiazolinone (Acticide OTW) wasadded to the render formulation via the make-up water.

Testing of Growth on the Exterior Wall:

Polystyrene foam boards which had been provided with a cement-containingreinforcing mortar were coated with the render formulations which hadbeen modified in the manner indicated using powders from Examples 1 and2 and from Comparative Examples 3 and 4 and were weathered in the openfor 11 months. The amount of growth formed on the boards was monitoredat regular intervals and evaluated qualitatively according to thefollowing scale: 0=no growth, +=small amount of growth, ++=moderateamount of growth, +++=large amount of growth. The results are summarizedin Table 2.

TABLE 2 Example 3 months 6 months 9 months 12 months Example 1 0 0 0 0Example 2 0 0 0 0 Comp. Ex. 3 0 + ++ +++ Comp. Ex. 4 0 0 + +

The examples demonstrate the excellent effectiveness of the treatmentaccording to the invention. Unprotected systems (Comparative Example 3)display a large amount of growth relatively early. The growth cannot becompletely suppressed even by direct addition of large amounts of activecompound (Comparative Example 4). The examples according to theinvention, on the other hand, show that reliable protection is ensureddespite a considerably lower active compound concentration (Ex. 1=22.5ppm, Ex. 2=10.5 ppm, Ex. 4=225 ppm of biocide, in each case based on theformulation).

1-10. (canceled)
 11. In a curable mineral construction productcontaining a film forming redispersible polymer powder, the improvementcomprising: employing as said redispersible polymer powder, aredispersible polymer powder composition comprising at least one filmforming redispersible polymer powder, and at least one biocide.
 12. Theconstruction product of claim 11, wherein said redispersible polymerpowder composition is prepared by spray drying an aqueous redispersiblepolymer dispersion and at least one biocide.
 13. The constructionproduct of claim 12, wherein biocide is added to said aqueousredispersible polymer dispersion prior to spray drying.
 14. Theconstruction product of claim 11 which contains a hydraulically settingmineral binder.
 15. The construction product of claim 11, wherein atleast one hydraulically setting binder is selected from the groupconsisting of cement, water glass, gypsum, and lime.
 16. Theconstruction product of claim 11, wherein at least one film formingpolymer comprises a polymer polymerized from one or more monomersselected from the group consisting of vinyl esters, (meth)acrylicesters, vinylaromatics, olefins, 1,3-dienes, vinyl halides, andoptionally, further monomers copolymerizable therewith.
 17. Theconstruction product of claim 11, wherein at least one film formingpolymer comprises a copolymer comprising vinyl acetate and ethylene, acopolymer comprising vinyl acetate, ethylene and a vinyl ester ofα-branched monocarboxylic acids having from 9 to 11 carbon atoms, or acopolymer comprising styrene and one or more of methyl acrylate, ethylacrylate, propyl acrylate, n-butyl acrylate, or 2-ethylhexyl acrylate.18. A process for increasing the resistance of cured mineral buildingproducts containing a biocide to microbial growth, comprising adding atleast one biocide in the form of a dry composition containing at leastone film forming redispersible polymer powder and at least one biocide.19. A process for the preparation of a curable, biocide-containingmineral building material of claim 11, comprising admixing a) one ormore mineral building composition components; b) water; and c) aredispersible polymer powder composition comprising at least one filmforming redispersible polymer powder and a biocidal additive of at leastone biocide, said biocidal component present in an amount of from 0.001to 0.5 weight percent based on the weight of the redispersible polymerpowder composition.
 20. The process of claim 19, wherein at least onebiocide is a fungicide.
 21. The process of claim 19, wherein anisothiazolinone, benzisothiazolinone or mixture thereof is used as abiocide.
 22. The process of claim 21, wherein at least one biocide isN-octylisothiazolinone.
 23. The process of claim 19, wherein thebiocide(s) are present in a total amount of from 0.001 to 0.1% byweight, based on the weight of the water-redispersible polymer powdercomposition.
 24. The process of claim 19, wherein at least one filmforming polymer is a polymer polymerized from one or more monomersselected from the group consisting of vinyl esters, (meth)acrylicesters, vinylaromatics, olefins, 1,3-dienes, vinyl halides, andoptionally, polymerized further monomers copolymerizable therewith. 25.The process of claim 24, wherein said film forming polymer comprises acopolymer comprising vinyl acetate and ethylene, a copolymer comprisingvinyl acetate, ethylene and a vinyl ester of α-branched monocarboxylicacids having from 9 to 11 carbon atoms, or a copolymer comprisingstyrene and one or more of methyl acrylate, ethyl acrylate, propylacrylate, n-butyl acrylate, or 2-ethylhexyl acrylate.
 26. The process ofclaim 19, wherein the water-redispersible polymer powder composition isobtained by mixing the biocide into the aqueous polymer dispersionsprior to drying or adding it after drying.
 27. The process of claim 19,wherein said mineral building composition component comprises one ormore hydraulically setting binders selected from the group consisting ofcement, water glass, gypsum, and lime.
 28. The process of claim 27,wherein said curable biocide mineral building material is a buildingadhesive selected from the group consisting of tile adhesives, thermalinsulation adhesives, plasters, renders, knifing fillers, flooringscreeds, leveling compositions, sealing slurries, jointing mortars,paints, and sealing grouts for tunnel construction and undergroundworks.
 29. The process of claim 19, wherein the mineral buildingcomposition components contain no hydraulically setting binders.